Is a /boot partition necessary anymore?
I was told to start partitioning during a Linux install with creating a 300 MB sized /boot partition. Does a separate /boot partition provide any advantages for the average user?
First, 300 Mb is almost certainly going to be too small in the long run.
To answer the question, no the "average" user does not need a separate /boot partition. It is, however, required for certain installations, most common user cases are LVM, Encryption (LUKS) and RAID.